Unsupervised soft clustering of high resolution airborne geophysical and satellite data suites from the Sperrgebiet, Karas Region, Southern Namibia, to enhance lithology mapping

Abstract

The Karas region is the southernmost region of Namibia extending between the Orange River in the south and latitude 25S in the north and from the South Atlantic Ocean in the west to the eastern border at longitude 20E. The geology of the Karas region is characterized by the pan-African Gariep Fold Belt in the west, the Meso-Proterozoic Namaqua Metamorphic Belt in the central area and south, and the Kalahari Craton in the northeast. The airborne magnetic and radiometric data were acquired with a flight line spacing of 200 m above ground and terrain clearance of 80 m. ASTER and Landsat imagery which completely cover the Karas Region were processed to match for integration with the airborne geophysical data. A novel data integration and classification tool recently developed (e.g. Paasche and Eberle 2011) has been used for automated and objective information extraction. The integrated data, i.e. a large set of multi-element vector samples - each of them carrying magnetic, radiometric, satellite band/hyperspectral and positioning information - has been grouped into a number of classes to provide a pseudo-lithology map. Spatial resolution of the pseudo-lithology map is considerably higher than that of conventional geological maps. High resolution data are thus considered a pre-requisite to identify new mineral exploration targets from this innovative integration technology. A few examples from different geological settings of the Karas region are discussed and compared with conventional mapping products, field trip evidence and geophysical ground truthing. Reference Paasche, H. and Eberle, D. 2011, doi:10/1071/EG11014